In fabricating a semiconductor device, the width of a metal wiring line may be reduced as the element of the semiconductor device becomes highly integrated. In order to increase the conductivity of the wiring line, a material such as copper (Cu) may be used. However, it is sometimes difficult to form copper using a present patterning process. Therefore, in many cases, a wiring line process of depositing aluminum by sputtering to perform patterning may be used. In order to increase the conductivity of the wiring line, copper can be partially included in the aluminum. When a target obtained by including copper from about 0.1% to about 0.5% in aluminum may be used in a sputtering process, a patterning process can be performed in the above containing amount of copper. The sputtering can be performed at a temperature between a range of 120° C. and 200° C., which is lower than in another layer deposition process such as chemical vapor deposition (CVD). When an Al—Cu sputtering deposition layer is left at a relatively low temperature for a long time, an Al—Cu thin film changes from a GP zone to a θ phase due to an aging effect so that the copper component in the Al—Cu thin film is extracted in the form of a particle. The copper extracted material may serve as an etching stop layer that prevents aluminum positioned under the particle from being etched when the Al—Cu thin film is reactive ion etched to form process defect in the form of a micro bridge between metal lines.
As illustrated in example FIG. 1, an enlarged side section and plane of a photograph is shown of a process defect in the form of a micro bridge caused by extracting copper in an Al—Cu sputtering thin film. As a result, since the defect deteriorates the function of the semiconductor device and reliability, when the defect is generated, a large number of process wafers are scraped. When process yield deteriorates due to an increase in a reject ratio, process cost and chip production cost increase.